WO2000054961A1 - Stripping method for an article in transparent polymer material and use for making an article in transparent polymer such as an ophthalmic lens - Google Patents

Stripping method for an article in transparent polymer material and use for making an article in transparent polymer such as an ophthalmic lens Download PDF

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Publication number
WO2000054961A1
WO2000054961A1 PCT/FR2000/000538 FR0000538W WO0054961A1 WO 2000054961 A1 WO2000054961 A1 WO 2000054961A1 FR 0000538 W FR0000538 W FR 0000538W WO 0054961 A1 WO0054961 A1 WO 0054961A1
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WO
WIPO (PCT)
Prior art keywords
article
mold
transparent polymer
temperature
polymerization
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Application number
PCT/FR2000/000538
Other languages
French (fr)
Inventor
Gil De Marignan
Gaston Derozier
Original Assignee
Essilor International
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Filing date
Publication date
Application filed by Essilor International filed Critical Essilor International
Priority to DE60002686T priority Critical patent/DE60002686T2/en
Priority to AU31713/00A priority patent/AU3171300A/en
Priority to AT00909420T priority patent/ATE240205T1/en
Priority to EP00909420A priority patent/EP1163106B1/en
Priority to JP2000605018A priority patent/JP4434496B2/en
Publication of WO2000054961A1 publication Critical patent/WO2000054961A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00009—Production of simple or compound lenses
    • B29D11/00038—Production of contact lenses
    • B29D11/00125—Auxiliary operations, e.g. removing oxygen from the mould, conveying moulds from a storage to the production line in an inert atmosphere
    • B29D11/00192—Demoulding, e.g. separating lenses from mould halves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C37/00—Component parts, details, accessories or auxiliary operations, not covered by group B29C33/00 or B29C35/00
    • B29C37/0003—Discharging moulded articles from the mould
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
    • B29C39/22—Component parts, details or accessories; Auxiliary operations
    • B29C39/36—Removing moulded articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00009—Production of simple or compound lenses
    • B29D11/00038—Production of contact lenses
    • B29D11/00125—Auxiliary operations, e.g. removing oxygen from the mould, conveying moulds from a storage to the production line in an inert atmosphere
    • B29D11/00192—Demoulding, e.g. separating lenses from mould halves
    • B29D11/00211—Demoulding, e.g. separating lenses from mould halves using heating means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00009—Production of simple or compound lenses
    • B29D11/00432—Auxiliary operations, e.g. machines for filling the moulds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/0002—Condition, form or state of moulded material or of the material to be shaped monomers or prepolymers

Definitions

  • the present invention generally relates to a method for demolding articles of transparent polymeric material, such as ophthalmic lenses (in particular for glasses), obtained by casting and polymerization of a liquid polymerizable composition in the cavity of a mold. in two parts.
  • ophthalmic lenses made of transparent polymer material are produced by casting and polymerization of a liquid polymerizable composition in the cavity formed between the two parts of a mineral glass mold, the whole being held by fixing means. such as clips.
  • This assembly is commonly called a "sandwich”.
  • the fixings are removed and the mold is removed to recover the ophthalmic lens.
  • liquid polymerizable compositions which can be used are very variable depending on the refractive index desired for the ophthalmic lens.
  • compositions for example the compositions comprising a monomer such as bis (allylcarbonate) of diethylene glycol (CR39®), present during their polymerization significant shrinkages of the order of 7% or more, and generally of 10% or more, which creates tension in the ophthalmic lens within the sandwich.
  • a monomer such as bis (allylcarbonate) of diethylene glycol (CR39®)
  • Certain ophthalmic lenses in particular lenses of positive optical power, may have, at random, visible defects during their subsequent coloring, for example by dipping in an aqueous dispersion of pigment. These faults are commonly called “ferns” because of their shape.
  • US-A-3,171,869 describes a method for removing mold from ophthalmic lenses obtained by polymerization of a liquid composition, in particular having a high polymerization shrinkage, which consists, just before the completion of the polymerization, of heating the sandwich to a temperature of 125 to 235 ° C to soften the material of the lens and simultaneously release the polymerization stress. During this heating, the polymerized material separates from the surface of the mold.
  • the demolding process reduces the risk of rupture of the molded lenses during demolding.
  • the separation between the molded lens and the mold surface which inevitably occurs during heating or shortly after cooling, induces stresses liable to cause the formation of ferns.
  • Document WO 97/39880 describes a method for manufacturing lenses comprising a step of heat transfer by conduction from the surface of the mold in order to increase the degree of surface polymerization of the lens for, during subsequent coloring, obtain a more homogeneous distribution of the dye on the surface of the lens.
  • the above object is achieved, according to the present invention, by a method of demolding an article of transparent polymer material formed in a cavity of a mold in two parts, by polymerization of a liquid polymerizable composition, characterized in that that he includes: a) uniform heating of the article in the mold, without separation of the article and the mold parts, to a demolding temperature of between Tg + 20 ° C and Tg + 80 ° C, preferably + 30 at + 60 ° C, where Tg is the glass transition temperature of the polymeric material; and b) applying an external mechanical force to separate at least one of the mold parts from the article while the latter is at said demolding temperature.
  • the demolding temperature is an important characteristic of the process of the invention.
  • the maximum limit of the demolding temperature is of the order of 160 ° C.
  • the demolding temperature will be of the order of 120 ° C. This uniform heating of the article is carried out for a duration generally of at least 30 minutes and preferably of at least 40 minutes.
  • the heating of the sandwich, and consequently of the molded article, to the release temperature can be done by any suitable means such as pure convection, application of infrared radiation, but is preferably done in a mixed infrared / convection manner. . Heating must be carried out as uniformly as possible in order to eliminate excessively large temperature gradients and so as to avoid premature mold release by thermal shock which lead to articles comprising numerous ferns. This is in particular the case of ophthalmic lenses having positive optical powers and especially high positive optical powers, for example greater than +3.00 diopters.
  • the temperature of the assembly of the mold is lowered to a temperature of 20 to 60 ° C.
  • the application of the external mechanical force of separation of the mold parts from the molded article can conveniently be carried out by means of a tool acting as a lever between the two mold parts.
  • FIG. 1 illustrating an embodiment of the disassembly operation of the mold parts according to the invention, after molding of the ophthalmic lens 1 of positive optical power, and removal, as is conventional, of the clips and joints maintaining the mold parts 2, 3 during molding, a tool 4 such as a spatula is inserted between these mold parts.
  • the tool 4 is inserted so as to be able to act as a lever, the pivot point of which is preferably the point of contact of the tool with the internal surface of the convex part 2 of the mold and a end of the tool brought into contact with the internal surface of the concave part 3 of the mold. Therefore, by applying to the free end of the tool a force in the direction indicated by arrow A, the tool, acting as a lever, exerts on the convex and concave mold parts 2, 3, forces external separation FI and F2, in opposite directions, ensuring a suitable separation of at least the concave part 3 of the mold while the ophthalmic lens 1 is at the demolding temperature.
  • the molds used are conventional molds for the production of ophthalmic lenses with positive optical power and consist of a convex part and a concave part made of mineral glass and a rubber seal kept closed with a clip.
  • the CR39® monomer is mixed with 2.5% PIP (isopropyl peroxy dicarbonate).
  • the assembly is filtered, degassed and then poured into an assembly consisting of two parts of mineral glass mold and a seal held by a metal clip.
  • the whole is polymerized in an oven with a thermal cycle of 17 hours.
  • the clips and joints were removed, the sandwiches washed with a dilute aqueous sodium hydroxide solution at ⁇ 70 ° C and after washing, the sandwiches were brushed to complete the cleaning.
  • the assemblies are generally at a temperature of 25 ° C to 50 ° C.
  • a first series of clean, dry sandwiches was subjected to the following conventional disassembly process.
  • the clean and dry sandwiches are reheated to around 70 ° C in an oven, then after leaving the oven, a spatula is inserted between the mold parts as described above and an external separation force is exerted by means of the spatula. .
  • the concave part of the mold separates from the lens, but generally the lens remains stuck to the convex part of the mold.
  • the lens is then separated from the convex part by blowing air and is recovered.
  • a second series of sandwiches was subjected to the disassembly process according to the invention, by heating the clean and dry sandwiches to 120 ° C. by means of the following cycle:
  • the sandwiches are then immediately disassembled at a temperature of 120 ° C. by means of a spatula slid between the mold parts and by proceeding as described above.
  • the concave part of the mold separates from the lens, while generally the lens remains stuck on the convex part.
  • the convex part of the mold is separated from the lens as above.
  • the two sets of lenses are then subjected to a coloring step consisting in immersing the lenses in an aqueous bath containing dyes in the dispersed state and maintained at a temperature close to 95 ° C.
  • the rate of appearance of ferns was determined for each series of lenses. It has been found that for lenses of the first series (conventional disassembly at 70 ° C.), the rate of appearance of ferns is approximately 50%, while for lenses of the second series, demolded by the process of invention, this rate was less than 2%.
  • the release method according to the invention allows a very significant reduction in the rate of appearance of ferns in ophthalmic lenses.

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  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Ophthalmology & Optometry (AREA)
  • Mechanical Engineering (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
  • Eyeglasses (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)

Abstract

The invention concerns a method which consists in: (a) heating the article uniformly in the mould, at a temperature ranging between Tg + 20 °C and Tg + 80 °C, where Tg is the glass transition temperature of the transparent polymer material, without separating the article and the mould parts; and (b) applying an external mechanical force for separating at least one of the mould parts from the article while the latter is at said stripping temperature.

Description

Procédé de démoulage d'un article en matériau polymère transparent et son utilisation pour la fabrication d'un article en matériau polymère transparent tel qu'une lentille ophtalmique. Method for demolding an article from transparent polymer material and its use for the manufacture of an article from transparent polymer material such as an ophthalmic lens.
La présente invention concerne de manière générale un procédé de démoulage d'articles en matériau polymère transparent, tels que des lentilles ophtalmiques (en particulier pour des lunettes), obtenus par coulée et polymérisation d'une composition liquide polymérisable dans la cavité d'un moule en deux parties.The present invention generally relates to a method for demolding articles of transparent polymeric material, such as ophthalmic lenses (in particular for glasses), obtained by casting and polymerization of a liquid polymerizable composition in the cavity of a mold. in two parts.
Traditionnellement, les lentilles ophtalmiques en matériau polymère transparent (verre organique) sont fabriquées par coulée et polymérisation d'une composition liquide polymérisable dans la cavité formée entre les deux parties d'un moule en verre minéral, le tout étant maintenu par des moyens de fixation tels que des clips. Cet assemblage est communément appelé "sandwich".Traditionally, ophthalmic lenses made of transparent polymer material (organic glass) are produced by casting and polymerization of a liquid polymerizable composition in the cavity formed between the two parts of a mineral glass mold, the whole being held by fixing means. such as clips. This assembly is commonly called a "sandwich".
Après polymérisation, on enlève les fixations et on procède au démoulage pour récupérer la lentille ophtalmique.After polymerization, the fixings are removed and the mold is removed to recover the ophthalmic lens.
Les compositions liquides polymérisables utilisables sont très variables selon l'indice de réfraction souhaité pour la lentille ophtalmique.The liquid polymerizable compositions which can be used are very variable depending on the refractive index desired for the ophthalmic lens.
Nombre de ces compositions, par exemple les compositions comprenant un monomère tel que le bis(allylcarbonate) de diéthylène glycol (CR39®), présentent lors de leur polymérisation des retraits importants de l'ordre de 7% ou plus, et généralement de 10% ou plus, ce qui crée des tensions dans la lentille ophtalmique au sein du sandwich.Number of these compositions, for example the compositions comprising a monomer such as bis (allylcarbonate) of diethylene glycol (CR39®), present during their polymerization significant shrinkages of the order of 7% or more, and generally of 10% or more, which creates tension in the ophthalmic lens within the sandwich.
Certaines lentilles ophtalmiques, en particulier des lentilles de puissance optique positive, peuvent présenter, de façon aléatoire, des défauts visibles lors de leur coloration ultérieure, par exemple par trempage dans une dispersion aqueuse de pigment. Ces défauts sont communément appelés "fougères" en raison de leur forme.Certain ophthalmic lenses, in particular lenses of positive optical power, may have, at random, visible defects during their subsequent coloring, for example by dipping in an aqueous dispersion of pigment. These faults are commonly called "ferns" because of their shape.
Ces défauts sont probablement dus à des relâchements brutaux des contraintes lors du démoulage, en particulier dans le cas des compositions présentant un retrait élevé à la polymérisation et des lentilles ophtalmiques de puissance optique positive.These defects are probably due to sudden relaxation of the stresses during demolding, in particular in the case of compositions having a high shrinkage upon polymerization and ophthalmic lenses of positive optical power.
Le brevet US-A-3 171 869 décrit un procédé de démoulage de lentilles ophtalmiques obtenues par polymérisation d'une composition liquide, en particulier présentant un retrait de polymérisation élevé, qui consiste juste avant l'achèvement de la polymérisation à chauffer le sandwich à une température de 125 à 235°C pour ramollir le matériau de la lentille et simultanément relâcher la contrainte de polymérisation. Durant ce chauffage, le matériau polymérisé se sépare de la surface du moule.US-A-3,171,869 describes a method for removing mold from ophthalmic lenses obtained by polymerization of a liquid composition, in particular having a high polymerization shrinkage, which consists, just before the completion of the polymerization, of heating the sandwich to a temperature of 125 to 235 ° C to soften the material of the lens and simultaneously release the polymerization stress. During this heating, the polymerized material separates from the surface of the mold.
Selon le brevet US-A-3 171 869, le procédé de démoulage réduit le risque de rupture des lentilles moulées lors du démoulage. Toutefois, la séparation entre la lentille moulée et la surface du moule qui intervient inévitablement lors du chauffage ou peu après le refroidissement, induit des contraintes susceptibles d'entraîner la formation de fougères.According to US-A-3,171,869, the demolding process reduces the risk of rupture of the molded lenses during demolding. However, the separation between the molded lens and the mold surface which inevitably occurs during heating or shortly after cooling, induces stresses liable to cause the formation of ferns.
Le document WO 97/39880 décrit un procédé de fabrication de lentilles comportant une étape de transfert thermique par conduction à partir de la surface du moule afin d'accroître le degré de polymérisation de surface de la lentille pour, lors d'une coloration ultérieure, obtenir une répartition plus homogène du colorant à la surface de la lentille.Document WO 97/39880 describes a method for manufacturing lenses comprising a step of heat transfer by conduction from the surface of the mold in order to increase the degree of surface polymerization of the lens for, during subsequent coloring, obtain a more homogeneous distribution of the dye on the surface of the lens.
Du fait du chauffage par conduction thermique à partir d'une surface du sandwich, il n'y a pas un chauffage homogène du sandwich, ce qui peut induire des contraintes dans la lentille polymérisée.Due to heating by thermal conduction from a surface of the sandwich, there is no homogeneous heating of the sandwich, which can induce stresses in the polymerized lens.
Il serait donc souhaitable de mettre au point un procédé de démoulage d'articles en matériau polymère transparent, tels que des lentilles, obtenus par polymérisation d'une composition liquide polymérisable dans la cavité d'un moule en deux parties qui diminue de façon significative le risque d'apparition de fougères et autres défauts lors de la coloration ultérieure des lentilles.It would therefore be desirable to develop a process for demolding articles made of transparent polymeric material, such as lenses, obtained by polymerization of a liquid polymerizable composition in the cavity of a two-part mold which significantly reduces the risk of ferns and other defects appearing during subsequent coloring of the lenses.
On atteint le but ci-dessus, selon la présente invention, par un procédé de démoulage d'un article en matériau polymère transparent formé dans une cavité d'un moule en deux parties, par polymérisation d'une composition liquide polymérisable, caractérisé en ce qu'il comprend : a) le chauffage uniforme de l'article dans le moule, sans séparation de l'article et des parties de moule, à une température de démoulage comprise entre Tg + 20°C etTg + 80°C, de préférence de + 30 à + 60°C, où Tg est la température de transition vitreuse du matériau polymère; et b) l'application d'une force mécanique externe pour séparer au moins une des parties de moule de l'article pendant que ce dernier se trouve à ladite température de démoulage. La température de démoulage est une caractéristique importante du procédé de l'invention. En effet, si la température est trop basse, il y aura un relâchement brutal des contraintes lors du démoulage et apparition de défauts de type fougères dans les articles, et si la température est trop élevée, il existe un risque important de rupture et/ou de jaunissement de l'article. En général, la limite maximum de la température de démoulage est de l'ordre de 160°C. A titre d'exemple, dans le cas de la fabrication de lentilles ORMA®, obtenu par polymérisation d'une composition liquide comprenant un monomère diallyl carbonate de diéthylène glycol, la température de démoulage sera de l'ordre de 120°C. Ce chauffage uniforme de l'article s'effectue pendant une durée généralement d'au moins 30 minutes et de préférence d'au moins 40 minutes.The above object is achieved, according to the present invention, by a method of demolding an article of transparent polymer material formed in a cavity of a mold in two parts, by polymerization of a liquid polymerizable composition, characterized in that that he includes: a) uniform heating of the article in the mold, without separation of the article and the mold parts, to a demolding temperature of between Tg + 20 ° C and Tg + 80 ° C, preferably + 30 at + 60 ° C, where Tg is the glass transition temperature of the polymeric material; and b) applying an external mechanical force to separate at least one of the mold parts from the article while the latter is at said demolding temperature. The demolding temperature is an important characteristic of the process of the invention. In fact, if the temperature is too low, there will be a sudden relaxation of the stresses during demolding and the appearance of fern-type defects in the articles, and if the temperature is too high, there is a significant risk of rupture and / or yellowing of the item. In general, the maximum limit of the demolding temperature is of the order of 160 ° C. By way of example, in the case of the production of ORMA® lenses, obtained by polymerization of a liquid composition comprising a diallyl carbonate monomer of diethylene glycol, the demolding temperature will be of the order of 120 ° C. This uniform heating of the article is carried out for a duration generally of at least 30 minutes and preferably of at least 40 minutes.
Le chauffage du sandwich, et par suite de l'article moulé, à la température de démoulage, peut se faire par tout moyen approprié tel que convection pure, application d'un rayonnement infrarouge, mais se fait de préférence de façon mixte infrarouge/convection. Le chauffage doit s'effectuer de la manière la plus uniforme possible afin d'éliminer des gradients de température trop importants et de manière à éviter des démoulages prématurés par choc thermique qui conduisent à des articles comportant de nombreuses fougères. C'est en particulier le cas des lentilles ophtalmiques ayant des puissances optiques positives et tout spécialement des puissances optiques positives élevées, par exemple supérieures à +3,00 dioptries.The heating of the sandwich, and consequently of the molded article, to the release temperature, can be done by any suitable means such as pure convection, application of infrared radiation, but is preferably done in a mixed infrared / convection manner. . Heating must be carried out as uniformly as possible in order to eliminate excessively large temperature gradients and so as to avoid premature mold release by thermal shock which lead to articles comprising numerous ferns. This is in particular the case of ophthalmic lenses having positive optical powers and especially high positive optical powers, for example greater than +3.00 diopters.
En général, avant la mise en œuvre du procédé de la présente invention et après polymérisation, la température de l'assemblage du moule est abaissée à une températurede 20 à 60°C.In general, before the implementation of the process of the present invention and after polymerization, the temperature of the assembly of the mold is lowered to a temperature of 20 to 60 ° C.
Bien que, selon le procédé de l'invention, généralement une seule des parties de moule soit séparée de l'article moulé lors de l'application de la force mécanique externe à la température de démoulage, l'autre partie étant séparée ultérieurement, il est possible de séparer simultanément les deux parties de moule de l'article moulé par l'application de cette force mécanique externe à la température de démoulage.Although, according to the method of the invention, generally only one of the mold parts is separated from the molded article when the external mechanical force is applied to the demolding temperature, the other part being separated later, it It is possible to simultaneously separate the two mold parts from the molded article by applying this external mechanical force to the demolding temperature.
L'application de la force mécanique externe de séparation des parties de moule de l'article moulé peut, de manière commode, s'effectuer au moyen d'un outil agissant comme un levier entre les deux parties de moule.The application of the external mechanical force of separation of the mold parts from the molded article can conveniently be carried out by means of a tool acting as a lever between the two mold parts.
Ainsi, comme le montre la figure 1, illustrant une réalisation de l'opération de désassemblage des parties de moule selon l'invention, après moulage de la lentille ophtalmique 1 de puissance optique positive, et enlèvement, comme cela est classique, des clips et des joints maintenant les parties de moule 2, 3 lors du moulage, on insère entre ces parties de moule un outil 4 tel qu'une spatule.Thus, as shown in FIG. 1, illustrating an embodiment of the disassembly operation of the mold parts according to the invention, after molding of the ophthalmic lens 1 of positive optical power, and removal, as is conventional, of the clips and joints maintaining the mold parts 2, 3 during molding, a tool 4 such as a spatula is inserted between these mold parts.
Comme le montre la figure 1, l'outil 4 est inséré de manière à pouvoir agir comme un levier dont le point de pivotement est de préférence le point de contact de l'outil avec la surface interne de la partie convexe 2 du moule et une extrémité de l'outil mise en contact avec la surface interne de la partie concave 3 du moule. De ce fait, en appliquant à l'extrémité libre de l'outil une force dans le sens indiqué par la flèche A, l'outil, agissant comme un levier, exerce sur les parties de moule convexe et concave 2, 3, des forces externes de séparation FI et F2, de sens opposés, assurant une séparation convenable d'au moins la partie concave 3 du moule alors que la lentille ophtalmique 1 se trouve à la température de démoulage. A la place de la spatule, on peut aussi utiliser une machine semi- automatique.As shown in FIG. 1, the tool 4 is inserted so as to be able to act as a lever, the pivot point of which is preferably the point of contact of the tool with the internal surface of the convex part 2 of the mold and a end of the tool brought into contact with the internal surface of the concave part 3 of the mold. Therefore, by applying to the free end of the tool a force in the direction indicated by arrow A, the tool, acting as a lever, exerts on the convex and concave mold parts 2, 3, forces external separation FI and F2, in opposite directions, ensuring a suitable separation of at least the concave part 3 of the mold while the ophthalmic lens 1 is at the demolding temperature. Instead of the spatula, you can also use a semi-automatic machine.
Les exemples suivants illustrent la présente invention. Les moules utilisés sont des moules classiques pour la fabrication de lentilles ophtalmiques de puissance optique positive et sont constitués d'une partie convexe et d'une partie concave en verre minéral et d'un joint en caoutchouc maintenus fermés à l'aide d'un clip.The following examples illustrate the present invention. The molds used are conventional molds for the production of ophthalmic lenses with positive optical power and consist of a convex part and a concave part made of mineral glass and a rubber seal kept closed with a clip.
On a moulé de manière classique des lentilles en verre organique ORMA® d'épaisseur 1,5 mm au centre, et de puissance +6 dioptries, au moyen des moules précédents. Le monomère CR39® est mélangé avec 2,5 % de PIP (péroxy dicarbonate d'isopropyle). L'ensemble est filtré, dégazé puis coulé dans un assemblage constitué par deux parties de moule en verre minéral et d'un joint maintenus par un clip métallique.ORMA® organic glass lenses 1.5 mm thick in the center, and with a power of +6 diopters, were conventionally molded using the preceding molds. The CR39® monomer is mixed with 2.5% PIP (isopropyl peroxy dicarbonate). The assembly is filtered, degassed and then poured into an assembly consisting of two parts of mineral glass mold and a seal held by a metal clip.
L'ensemble est polymérisé dans une étuve avec un cycle thermique de 17 heures.The whole is polymerized in an oven with a thermal cycle of 17 hours.
Après polymérisation, on a retiré les clips et les joints, lavé les sandwichs avec une solution aqueuse diluée de soude à ~ 70°C et après lavage, on a brossé les sandwichs pour parfaire le nettoyage.After polymerization, the clips and joints were removed, the sandwiches washed with a dilute aqueous sodium hydroxide solution at ~ 70 ° C and after washing, the sandwiches were brushed to complete the cleaning.
En fin de lavage, brassage, les assemblages (sandwichs) sont généralement à une température de 25°C à 50°C.At the end of washing, stirring, the assemblies (sandwiches) are generally at a temperature of 25 ° C to 50 ° C.
On a soumis une première série de sandwichs propres et secs au procédé de désassemblage classique suivant.A first series of clean, dry sandwiches was subjected to the following conventional disassembly process.
Les sandwichs propres et secs sont réchauffés à environ 70°C dans une étuve, puis après sortie de l'étuve, on insère entre les parties de moule comme décrit précédemment, une spatule et on exerce une force de séparation externe au moyen de la spatule.The clean and dry sandwiches are reheated to around 70 ° C in an oven, then after leaving the oven, a spatula is inserted between the mold parts as described above and an external separation force is exerted by means of the spatula. .
La partie concave du moule se sépare de la lentille cependant que généralement la lentille reste collée à la partie convexe du moule.The concave part of the mold separates from the lens, but generally the lens remains stuck to the convex part of the mold.
On sépare alors la lentille de la partie convexe par soufflage d'air et on la récupère.The lens is then separated from the convex part by blowing air and is recovered.
(On peut alors réassembler les parties de moule avec un nouveau joint en prenant soin d'éviter l'introduction de poussière, et procéder au moulage d'une nouvelle lentille en procédant comme précédemment).(We can then reassemble the mold parts with a new seal, taking care to avoid the introduction of dust, and proceed to molding a new lens by proceeding as above).
On a soumis une seconde série de sandwichs au procédé de désassemblage selon l'invention, en réchauffant les sandwichs propres et secs à 120°C au moyen du cycle suivant :A second series of sandwiches was subjected to the disassembly process according to the invention, by heating the clean and dry sandwiches to 120 ° C. by means of the following cycle:
1. Passage dans une première étuve à 80°C (durée 30 à 45 minutes)1. Passage in a first oven at 80 ° C (duration 30 to 45 minutes)
2. Passage dans une seconde étuve à 100-110°C (durée 30 à 45 minutes) 3. Exposition à un rayonnement infrarouge pour atteindre 120°C environ (durée 50 secondes).2. Passage in a second oven at 100-110 ° C (duration 30 to 45 minutes) 3. Exposure to infrared radiation to reach approximately 120 ° C (duration 50 seconds).
Les sandwichs sont alors immédiatement désassemblés à la température de 120°C au moyen d'une spatule glissée entre les parties de moule et en procédant comme décrit ci-dessus.The sandwiches are then immediately disassembled at a temperature of 120 ° C. by means of a spatula slid between the mold parts and by proceeding as described above.
La partie concave du moule se sépare de la lentille, cependant que généralement la lentille reste collée sur la partie convexe.The concave part of the mold separates from the lens, while generally the lens remains stuck on the convex part.
Après refroidissement, on sépare la partie convexe du moule de la lentille comme ci-dessus. Les deux séries de lentilles sont ensuite soumises à une étape de coloration consistant à immerger les lentilles dans un bain aqueux renfermant des colorants à l'état dispersé et maintenu à une température proche de 95°C.After cooling, the convex part of the mold is separated from the lens as above. The two sets of lenses are then subjected to a coloring step consisting in immersing the lenses in an aqueous bath containing dyes in the dispersed state and maintained at a temperature close to 95 ° C.
On a déterminé pour chacune des séries de lentilles le taux d'apparition de fougères. On a trouvé que pour les lentilles de la première série (désassemblage classique à 70°C), le taux d'apparition de fougères est de 50% environ, alors que pour les lentilles de la seconde série, démoulées par le procédé de l'invention, ce taux était inférieur à 2 %.The rate of appearance of ferns was determined for each series of lenses. It has been found that for lenses of the first series (conventional disassembly at 70 ° C.), the rate of appearance of ferns is approximately 50%, while for lenses of the second series, demolded by the process of invention, this rate was less than 2%.
Ainsi, le procédé de démoulage selon l'invention permet une réduction très importante du taux d'apparition de fougères dans des lentilles ophtalmiques. Thus, the release method according to the invention allows a very significant reduction in the rate of appearance of ferns in ophthalmic lenses.

Claims

REVENDICATIONS
1. Procédé de démoulage d'un article en matériau polymère transparent formé dans une cavité d'un moule en deux parties par polymérisation d'une composition polymérisable liquide, caractérisé en ce qu'il comprend : a) le chauffage uniforme de l'article dans le moule, à une température de démoulage comprise entre Tg 4- 20°C et Tg + 80°C, où Tg est la température de transition vitreuse du matériau polymère transparent, sans séparation de l'article et des parties de moule; et b) l'application d'une force mécanique externe pour séparer au moins une des parties de moule de l'article pendant que ce dernier se trouve à ladite température de démoulage.1. Method for demolding an article of transparent polymer material formed in a cavity of a two-part mold by polymerization of a liquid polymerizable composition, characterized in that it comprises: a) uniform heating of the article in the mold, at a demolding temperature between Tg 4- 20 ° C and Tg + 80 ° C, where Tg is the glass transition temperature of the transparent polymer material, without separation of the article and the mold parts; and b) applying an external mechanical force to separate at least one of the mold parts from the article while the latter is at said demolding temperature.
2. Procédé selon la revendication 1, caractérisé en ce que le chauffage uniforme de l'article dans le moule s'effectue pendant une durée d'au moins 30 minutes, de préférence d'au moins 40 minutes. 2. Method according to claim 1, characterized in that the uniform heating of the article in the mold is carried out for a period of at least 30 minutes, preferably at least 40 minutes.
3. Procédé de démoulage selon la revendication 1 ou 2, caractérisé en ce que le matériau polymère transparent présente un retrait de polymérisation d'au moins 7% et de préférence d'au moins 10%.3. Release process according to claim 1 or 2, characterized in that the transparent polymer material has a polymerization shrinkage of at least 7% and preferably at least 10%.
4. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce que le matériau polymère transparent résulte de la polymérisation d'une composition liquide polymérisable comprenant un monomère diallyl carbonate de diéthylène glycol.4. Method according to any one of claims 1 to 3, characterized in that the transparent polymer material results from the polymerization of a polymerizable liquid composition comprising a diallyl diethylene glycol glycate monomer.
5. Procédé selon l'une quelconque des revendications 1 à 4, caractérisé en ce que l'application de la force mécanique externe s'effectue au moyen d'un outil agissant comme un levier sur les parties de moule.5. Method according to any one of claims 1 to 4, characterized in that the application of the external mechanical force is carried out by means of a tool acting as a lever on the mold parts.
6. Procédé selon la revendication 5, caractérisé en ce que les parties de moule comprennent une partie convexe et une partie concave.6. Method according to claim 5, characterized in that the mold parts comprise a convex part and a concave part.
7. Procédé selon la revendication 6, caractérisé en ce que l'outil agissant comme un levier a un point de pivotement situé sur la partie convexe.7. Method according to claim 6, characterized in that the tool acting as a lever has a pivot point located on the convex part.
8. Procédé selon la revendication 7, caractérisé en ce que seule la partie concave est séparée de l'article moulé lors de l'application de la force mécanique externe. 8. Method according to claim 7, characterized in that only the concave part is separated from the molded article during the application of external mechanical force.
9. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que l'article est une lentille ophtalmique.9. Method according to any one of the preceding claims, characterized in that the article is an ophthalmic lens.
10. Procédé selon la revendication 9, caractérisé en ce que la lentille ophtalmique est une lentille de puissance optique positive. 10. Method according to claim 9, characterized in that the ophthalmic lens is a lens of positive optical power.
11. Procédé selon l'une quelconque des revendications 1 à 10, caractérisé en ce qu'après polymérisation, et avant la mise en œuvre du procédé selon l'une quelconque des revendications 1 à 10, la température de l'assemblage est abaissée à une température de 20 à 60°C.11. Method according to any one of claims 1 to 10, characterized in that after polymerization, and before the implementation of the method according to any one of claims 1 to 10, the temperature of the assembly is lowered to a temperature of 20 to 60 ° C.
12. Procédé selon l'une quelconque des revendications 1 à 11, caractérisé en ce que la température de démoulage est comprise entre Tg12. Method according to any one of claims 1 to 11, characterized in that the demolding temperature is between Tg
+ 30°C et Tg + 60°C.+ 30 ° C and Tg + 60 ° C.
13. Procédé de fabrication d'un article moulé en matériau polymère transparent, comprenant le coulage d'une composition liquide polymérisable dans une cavité d'un moule en deux parties et la polymérisation de la composition coulée pour former l'article moulé, caractérisé en ce que l'article moulé est démoulé par le procédé selon l'une quelconque des revendications 1 à 12.13. A method of manufacturing a molded article of transparent polymeric material, comprising the casting of a liquid polymerizable composition in a cavity of a mold in two parts and the polymerization of the cast composition to form the molded article, characterized in that the molded article is removed from the mold by the process according to any one of claims 1 to 12.
14. Procédé pour réduire le taux d'articles moulés en matériau polymère transparent inaptes à un traitement ultérieur de coloration, caractérisé en ce que les articles moulés sont fabriqués selon le procédé de la revendication 13. 14. Method for reducing the rate of molded articles made of transparent polymer material unsuitable for further coloring treatment, characterized in that the molded articles are produced according to the method of claim 13.
PCT/FR2000/000538 1999-03-17 2000-03-03 Stripping method for an article in transparent polymer material and use for making an article in transparent polymer such as an ophthalmic lens WO2000054961A1 (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
DE60002686T DE60002686T2 (en) 1999-03-17 2000-03-03 METHOD FOR REMOVING A TRANSPARENT OBJECT, AND ITS APPLICATION FOR PRODUCING AN OBJECT FROM TRANSPARENT PLASTIC, E.g. A CONTACT LENS
AU31713/00A AU3171300A (en) 1999-03-17 2000-03-03 Stripping method for an article in transparent polymer material and use for making an article in transparent polymer such as an ophthalmic lens
AT00909420T ATE240205T1 (en) 1999-03-17 2000-03-03 METHOD FOR DEFORMING A TRANSPARENT OBJECT AND ITS APPLICATION FOR PRODUCING AN OBJECT FROM A TRANSPARENT PLASTIC, SUCH AS A CONTACT LENS
EP00909420A EP1163106B1 (en) 1999-03-17 2000-03-03 Demoulding method for an article made of transparent polymer material and use for making a transparent polymer article such as an ophthalmic lens
JP2000605018A JP4434496B2 (en) 1999-03-17 2000-03-03 Method for removing a member made of transparent polymer material and its use for producing a member made of transparent polymer such as an optical lens

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9903291A FR2790993B1 (en) 1999-03-17 1999-03-17 METHOD FOR UNMOLDING AN ARTICLE OF TRANSPARENT POLYMER MATERIAL AND ITS USE FOR THE MANUFACTURE OF AN ARTICLE OF TRANSPARENT POLYMER MATERIAL SUCH AS AN OPHTHALMIC LENS
FR99/03291 1999-03-17

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US6171529B1 (en) 2001-01-09
DE60002686D1 (en) 2003-06-18
EP1163106B1 (en) 2003-05-14
DE60002686T2 (en) 2004-03-25
AU3171300A (en) 2000-10-04
EP1163106A1 (en) 2001-12-19
JP4434496B2 (en) 2010-03-17
FR2790993A1 (en) 2000-09-22
ATE240205T1 (en) 2003-05-15
JP2002538995A (en) 2002-11-19
FR2790993B1 (en) 2001-06-15

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